Skip to main content

Vacuum brazing – what is it?

This is the process of combining metals in vacuum furnaces with brazing materials. It is characterized by high purity, no overheating or stresses and very high resistance of the resulting connection. You can combine brazing and hardening treatments in a single cycle.

What is vacuum brazing?

This is a method of permanent metal bonding, which is based on the use of vacuum furnaces and a suitable binder (also called a solder or flux). The melting agents used to achieve a durable solder connection are generally characterized by a lower melting point than that of the metals which are being combined. Vacuum brazing is now considered to be one of the most modern and yet reliable methods of combining. This technique is very popular due to high purity, precision and durability of the resulting connection. In addition, it allows brazing and hardening processes to be combined into a single cycle, making production more efficient.

What are the differences between hard and soft soldering?

Steel brazing is a process that requires the use of a solder with a melting point exceeding 450°C. However, this technique is not suitable for all metals that have a lower melting point (e.g. lead or zinc). It can also be used in situations requiring the combination of brass alloys, copper, aluminum or steel. Soft soldering is a method in which the solder has a melting point lower than 450 °C.

What are the advantages of vacuum brazing?

What are the advantages of vacuum brazing? Vacuum brazing is undoubtedly one of the most reliable bonding methods and is valued primarily for:

– lack of a non-uniform structure caused by passing weld zones
– the option of mixing different materials
– no contamination of base materials
– high durability of the resulting joint
– no corrosion related issues
– low stresses
– no overheating during part processing
– the ability to carry out brazing and hardening processes in one cycle

The vacuum brazing technique is an excellent addition to more traditional welding techniques, which are increasingly being replaced by modern technological solutions. With professional vacuum furnaces and the knowledge and expertise of Sacher’s specialists, we are able to provide comprehensive support in the field of vacuum brazing. If you have any questions or concerns, please contact us by phone or email.

What is hard soldering?

Hard soldering, as we have mentioned before, requires the use of a solder with a melting point above 450°C. This method is most commonly used for carbon, tungsten, chrome, molybdenum, nickel, carbide plates and precious metals (e.g. gold, silver and copper). Specialist tools such as an oxyacetylene welding torch and a soldering lamp are required for hard soldering, but similar effects can also be achieved by using a smithy forge or electric induction. One of the most important issues in this method is the choice of suitable soldering material. This directly translates into the durability of the connection and helps avoid the possibility that the solder will not enter the gaps. It is also worth noting that a suitably dissolved flux increases anti-corrosion resistance and minimizes the risk of oxidation.

Hard soldering – types of bonding materials

Hard solders may at first glance resemble welding electrodes, which is due to the presence of flux coating. Due to the basic component of the material, as many as 8 solder classes can be distinguished:

AL Class– Aluminum brazing is used primarily for soldering aluminum alloys characterized by a higher melting point. Soldering materials of this class begin to melt at approximately 600°C.

AG Class – Silver brazing is among the most versatile types of solder connections. This class has a fairly wide melting range (450 to 1000 °C) which depends on the remaining additives.

CP Class – Copper-phosphorus brazing is ideal for copper, brass or bronze connections. This class is characterized by good electrical conductivity and high durability. Brazing brass with this type of solder requires a temperature of 650-900°C

CU Class – Copper brazing without additives is a great solution for soldering steel, nickel, copper alloys and zinc. Copper brazing becomes possible after reaching a temperature of about 1070°C.

NI Class – Nickel brazing is the most commonly used for joining stainless steel and molybdenum alloys, tungsten and cobalt. The temperature range in this case varies between 875 and 1100°C.

CO Class – Cobalt brazing is primarily used in the process of hard soldering cobalt, which starts to melt at about 1500°C.

AU Class – Gold brazing has a very high resistance to oxidation at high temperatures. Solders in this class typically contain an additional alloying element in the form of copper or nickel.

PD Class – Palladium brazing contains no more than 60% of this element because it is enriched with silver or copper. The joints formed by solders of this class are characterized by good vacuum tightness and wettability.